He was the USSR Armed Forces Champion in 1962 and Russian Champion in 1963. He finished equal first at Moscow 1970, and won the 1971 Moscow championship after a play-off. He placed first at Cienfuegos 1972, first at Novi Sad 1972, first at Novi Sad 1973, and equal first at Grand Manan 1984.
In 1976 Lein emigrated to the United States and played on the U.S. team in the 1978 Olympiad.
After immigrating to the United States, he represented the U.S. in several major national and international tournaments, finishing equal first at the U.S. Open and the World Open in 1976 and representing the U.S. at the 1978 Olympiad. Lein was New Jersey champion from 1992 through 1994.
In his prime, Lein was capable of beating anyone in the world. Among his victims were two World Champions, Mikhail Tal and Vassily Smyslov. He also scored wins against such world class Grandmasters as David Bronstein, Lev Polugaevsky, Leonid Stein, and Mark Taimanov.
In the 1970s Lein was a feared competitor in US Swiss tournaments (along with his compatriot ex-patriot GM Leonid Shamkovich). Lein had an imposing presence and was a burly fellow who looked like a weight lifter. During those days, before giving up the habit, he was a chain smoker and I remember seeing him at a tournament standing with his hands clasped behind his back and repeatedly tapping the lighted end of his cigarette with his index finger. These days Lein is retired and lives in a Cleveland, Ohio suburb but still gives lessons.